package com.telcordia.cvas.rpn;

import static org.junit.Assert.*;

import org.junit.Before;
import org.junit.Test;

public class RpnCalculatorTest {
	private RpnCalculator rpnCalculator;

	@Before
	public void init() {
		rpnCalculator = new RpnCalculator();
	}
	
	@Test
	public void addNoNumbersResultsIn0() {
		rpnCalculator.add();
		assertEquals(0, rpnCalculator.getXRegister());
	}
	
	@Test
	public void canAddTwoNumbers() {
		rpnCalculator.setXRegister(3);
		rpnCalculator.enter();
		rpnCalculator.setXRegister(4);
		rpnCalculator.add();
		assertEquals(7, rpnCalculator.getXRegister());
	}
	
	@Test
	public void canSetXRegister() {
		rpnCalculator.setXRegister(42);
		assertEquals(42, rpnCalculator.getXRegister());
	}
	
	@Test
	public void initiallyHasZero() {
		assertEquals(0, rpnCalculator.getXRegister());
	}
}
